Preheat oven to 350°F. In a large skillet over medium-high heat, cook the ground beef and onion, crumbling the beef as it cooks for 5 to 7 minutes. Drain any excess liquid.

Add the Mexican seasoning and beans and heat through. Add salt and pepper, to taste. Set aside.

In a medium bowl, mix the tomato sauce with the sour cream. Spread half of the sauce mixture onto the bottom of a 9" x 13" baking dish.

Add a layer of 3 flour tortillas on top, making smaller pieces and overlapping them until fully covered.

Top with a layer of shredded cheese (about 1 cup).

Add a layer of the ground beef mixture (about half of it).

Repeat all layers 1 more time (sauce mixture, 3 remaining tortillas, 1 cup cheese and the remaining ground beef).

Finally, top with the remaining cheese and peppers.

Bake for about 25 to 35 minutes, until the cheese is melted and bubbly.

Let stand for a few minutes before serving. Garnish with fresh cilantro.